1. Field of the Invention
The present invention relates to a rotary output transmitting structure, which may be used for a motor, more particularly, to a structure in which a slidable washer is placed between a gear wheel and a gear housing.
2. Related Art
In a conventional motor which may be used as the opening and closing drive for a window glass of a vehicle, a rotating speed of the rotor of a motor is reduced through a reduction gear and a driving force is transferred to an output shaft. More particularly, the rotating speed of the rotor is reduced through a gear wheel meshed with the worms formed on the rotor shaft so that driving force is transferred to the output shaft.
On the other hand, a gear housing to store the reduction gear is generally made by resin molding to be light in weight, and has a boss part integrally molded at the center thereof. While the motor is driven and the gear wheel rotates, an inner circumferential face of the gear wheel slides on an outer circumferential face of the boss part.
However, since the boss part is integrally molded with the gear housing made of resin, a sliding friction between the outer circumferential face of the boss part and the inner circumferential face of the gear wheel causes the wear of the outer circumferential face of the boss part, and consequently causes scattering of worn powders from the boss part.
Further, according to another conventional motor with a reduction gear disclosed in Japanese Utility Model Laid-Open NO. 6-5361, a sliding metallic washer is provided between an inner circumferential face of a gear wheel and an outer circumferential face of a boss part of a gear housing so that the resistance to wear is improved. However, since the metallic slidable washer placed in the spacing between the inner circumferential face of the gear wheel and the outer circumferential face of the boss part is formed in a cylindrical shape, the washer tends to incline toward the axial direction of the boss part. Therefore, when the motor is driven, it has a problem that the inclination leads to backlash and the inner circumferential face of the gear wheel cannot move smoothly on the outer circumferential face of the boss part. Furthermore, the sliding friction occurs at a place at which the slidable washer is not placed between the side of the gear wheel and the base of the gear housing, and may lead to scattering of worn powders from the gear housing.